Ultrasound diagnostic apparatus, method of transmitting and receiving ultrasonic wave, and program for transmitting and receiving ultrasonic wave

ABSTRACT

An ultrasound diagnostic apparatus includes plural ultrasound transducers which perform transmission and reception of ultrasonic waves toward a target site of a subject containing a puncture needle. A method of transmitting and receiving an ultrasonic wave uses the ultrasound transducers. The apparatus and the method form an ultrasonic beam to be transmitted from a transmit aperture set on the ultrasound transducers, acquire information relating to a specular-reflective component of the ultrasonic beam in the puncture needle, set a first receive aperture different from the transmit aperture set on the ultrasound transducers on the basis of the information relating to the specular-reflective component of the ultrasonic beam, and process an ultrasonic echo signal received by the ultrasound transducers using the first receive aperture.

BACKGROUND OF THE INVENTION

The present invention relates to an ultrasound diagnostic apparatuswhich diagnoses the inside of a subject, such as a human body, using anultrasound probe having a plurality of ultrasound transducers, a methodof transmitting and receiving an ultrasonic wave which transmits andreceives an ultrasonic wave from an ultrasound probe to a subject, aprogram for transmitting and receiving an ultrasonic wave which causes acomputer to execute a plurality of steps of the method of transmittingand receiving an ultrasonic wave, that is, a plurality of steps oftransmitting and receiving an ultrasonic wave, and a computer readablerecording medium having recorded therein the program for transmittingand receiving an ultrasonic wave. In particular, the present inventionrelates to a technique for allowing paracentesis or the like in which apuncture needle is inserted into a subject while viewing an ultrasoundimage.

An ultrasound vibrator which is used in an ultrasound diagnosticapparatus is formed by integrating a plurality of ultrasound transducers(vibrators). A transmit aperture and a receive aperture are set on eachof a plurality of ultrasound transducers at the time of transmission andreception of an ultrasonic wave, and the delay time (delay amount) ofeach of the transmission output of the transmit aperture and thereception output of the receive aperture of each ultrasound transduceris appropriately controlled for each ultrasound transducer. Anultrasonic transmission beam and an ultrasonic reception beam arerespectively synthesized to obtain ultrasound reception image data.

An ultrasound diagnostic apparatus is known which has a structure(puncture adapter) in which a puncture needle can be attached to anultrasound probe such that a biopsy on a specific site in a subject as ameasurement target can be easily performed using a dedicated punctureneedle. In this apparatus, a guideline when the puncture needle isinserted is displayed on a display. If the ultrasound diagnosticapparatus is operated using the ultrasound probe while the punctureneedle is inserted into the subject in accordance with the guideline, anoperator can simultaneously confirm an image in the subject and themotion of the puncture needle on the display, thereby performing safeparacentesis (biopsy, drainage, or the like).

However, in the ultrasound diagnostic apparatus of the related art,there is a problem that the intensity of an echo signal from thepuncture needle is weak depending on the entrance angle of the punctureneedle, and the image of the puncture needle is difficult to view on thedisplay. As a method of solving this problem, a technique is known inwhich the surface of the tip of the puncture needle is processed roughly(roughened). However, this technique has a problem in that an echosignal from other than the tip of the puncture needle is notsufficiently intensified, and it is not sufficient to intensify the echosignal itself.

For this reason, JP 9-28708 A describes a technique which, when apuncture needle is inserted into a subject, adjusts the transmissionbeam direction of an ultrasound scan beam at substantially a right anglewith respect to the entrance path of the puncture needle, and controlsthe delay amount of the output of each ultrasound transducer such thatthe transmission beam focal point position of each scan beam is in thevicinity of the position of the puncture needle.

SUMMARY OF THE INVENTION

On the other hand, in the technique described in JP 9-28708 A, with thedirection and focal point control of the transmission beam of theultrasound scan beam, an ultrasonic echo signal of a target line, suchas a line of the puncture needle entering the subject, can beintensified, but there is a problem in that transmission and receptioncontrol is significantly complicated.

In the technique described in JP 9-28708 A, the directionality of thereception beam of the ultrasound scan beam, or the like is notsufficiently taken into consideration, and there is a problem in thatthe effect of improving the intensity of the echo signal from thepuncture needle is not sufficient. For example, in the techniquedescribed in JP 9-28708 A, there is a problem in that, if the insertionangle of the puncture needle increases, the specular-reflectivecomponent of the transmission beam is out of the receive aperture set onthe plurality of ultrasound transducers at the time of reception, andthe echo signal from the puncture needle may not be sufficientlyreceived, thereby causing the intensity of the echo signal to beweakened.

Further, there is also a problem that since the transmission of anultrasound scan beam is a steer transmission inclined with respect tothe surface of the subject, the quality of the image other than of thepuncture needle deteriorates even where the visibility of the punctureneedle can be improved.

In the technique described in JP 9-28708 A, since the ultrasonic echosignal from the puncture needle is not directly stored, there is aproblem in that, at the time of an image process after reception, theintensity of the ultrasonic echo signal from the puncture needle may notbe improved, and thus the visibility of the puncture needle may not beimproved.

The invention has been finalized in consideration of the above-describedsituation, and an object of the invention is to provide an ultrasounddiagnostic apparatus, a method of transmitting and receiving anultrasonic wave, a program for transmitting and receiving an ultrasonicwave, and a recording medium capable of increasing the intensity of anultrasonic echo signal from a puncture needle and improving visibilityof the puncture needle.

To achieve the above object, an ultrasound diagnostic apparatusaccording to a first aspect of the invention is configured to comprise aplurality of ultrasound transducers which performs transmission andreception of ultrasonic waves toward a target site of a subjectcontaining a puncture needle; transmission control means for forming anultrasonic beam to be transmitted from a transmit aperture set on theplurality of ultrasound transducers; acquisition means for acquiringinformation relating to a specular-reflective component of theultrasonic beam in the puncture needle; reception control means forsetting a first receive aperture different from the transmit apertureset on the plurality of ultrasound transducers on the basis of theinformation relating to the specular-reflective component of theultrasonic beam; and reception signal processing means for processing anultrasonic echo signal received by the plurality of ultrasoundtransducers using the first receive aperture.

Preferably, the acquisition means acquires the information relating tothe specular-reflective component from the positional relationshipbetween the plurality of ultrasound transducers and the puncture needle.

Preferably, the acquisition means acquires the information relating tothe specular-reflective component from the insertion angle of thepuncture needle inserted into the subject with respect to the pluralityof ultrasound transducers.

It is preferable that the transmission control means forms theultrasonic beam to be deflected and that the acquisition means acquiresthe information relating to the specular-reflective component from theinsertion angle of the puncture needle and the deflection angle of theultrasonic beam.

Preferably, the reception signal processing means performs a weightingprocess on the ultrasonic echo signal to highlight thespecular-reflective component.

Preferably, the reception signal processing means further includes astorage unit which temporarily stores the ultrasonic echo signal.

It is preferable that the reception signal processing means furtherincludes a storage unit which temporarily stores the ultrasonic echosignal, performs weighting processing for enhancing a subject tissuecomponent on the ultrasonic echo signal, and synthesizes this ultrasonicecho signal on which weighting processing for enhancing a subject tissuecomponent has been performed and an ultrasonic echo signal on whichweighting processing for enhancing the specular-reflective component hasbeen performed.

Preferably, the reception control means sets the first receive apertureso as to contain ultrasound transducers located on a side opposite withrespect to the transmit apertures from an insertion position at whichthe puncture needle is introduced into a subject.

It is preferable that the reception signal control means sets a secondreceive aperture different from the first receive aperture andsynthesizes the ultrasonic echo signals obtained using the first receiveaperture and the second receive aperture in accordance with multipletimes of transmission by the transmit aperture.

It is preferable that the reception control means sets a plurality ofdivision receive apertures discontinuously divided on the plurality ofultrasound transducers as the first receive aperture, that there is atleast one ultrasound transducer not used as receive aperture between twoadjacent division receive apertures, and that the reception signalprocessing means synthesizes the ultrasonic echo signals obtained usingthe plurality of division receive apertures for one transmission by thetransmit apertures.

To achieve the above object, a method of transmitting and receiving anultrasonic wave according to a second aspect of the invention isconfigured as a method of transmitting and receiving an ultrasonic wavetoward a target site of a subject containing a puncture needle using aplurality of ultrasound transducers, the method comprising the steps offorming an ultrasonic beam to be transmitted from a transmit apertureset on the plurality of ultrasound transducers; transmitting the formedultrasonic beam toward the target site of the subject; acquiringinformation relating to a specular-reflective component of theultrasonic beam in the puncture needle; setting a first receive aperturedifferent from the transmit aperture on the plurality of ultrasoundtransducers on the basis of the information relating to thespecular-reflective component of the ultrasonic beam; receiving anultrasonic echo signal of the ultrasonic beam by plurality of ultrasoundtransducers using the set first receive aperture; and processing theultrasonic echo signal received by the plurality of ultrasoundtransducers using the first receive aperture.

To achieve the above object, a program for transmitting and receiving anultrasonic wave according to a third aspect of the invention isconfigured as a program for transmitting and receiving an ultrasonicwave for causing a computer to execute the individual steps oftransmitting and receiving an ultrasonic wave according to theabove-mentioned second aspect of the invention as steps of transmittingand receiving an ultrasonic wave toward a target site of a subjectcontaining a puncture needle using a plurality of ultrasoundtransducers. Thus, this aspect is a program for transmitting andreceiving an ultrasonic wave which causes a computer to execute aplurality of steps for transmitting and receiving an ultrasonic wavetoward a target site of a subject containing a puncture needle using aplurality of ultrasound transducers, wherein the plurality of stepsincludes the steps of forming an ultrasonic beam to be transmitted froma transmit aperture set on the plurality of ultrasound transducers,transmitting the formed ultrasonic beam toward the target site of thesubject, acquiring information relating to a specular-reflectivecomponent of the ultrasonic beam in the puncture needle, setting a firstreceive aperture different from the transmit aperture on the pluralityof ultrasound transducers on the basis of the information relating tothe specular-reflective component of the ultrasonic beam, receiving anultrasonic echo signal of the ultrasonic beam by the plurality ofultrasound transducers using the set first receive aperture, andprocessing the ultrasonic echo signal received by the plurality ofultrasound transducers using the first receive aperture.

To achieve the above object, a recording medium according to a fourthaspect of the invention is configured as a computer readable recordingmedium on which the program for transmitting and receiving an ultrasonicwave according to the above-mentioned third aspect of the invention isrecorded.

According to the invention, it is possible to increase the intensity ofthe echo signal from the puncture needle and to improve the visibilityof the puncture needle.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view showing an example of the mainconfiguration of an ultrasound diagnostic apparatus according toEmbodiment 1 of the invention.

FIG. 2 is a block diagram showing the main configuration of theultrasound diagnostic apparatus shown in FIG. 1.

FIG. 3 is a schematic view showing the geometric relationship between atransmitted ultrasonic wave and a reflected ultrasonic wave in anultrasound probe of the related art.

FIG. 4 is a schematic view illustrating the basic concept of a method oftransmitting and receiving an ultrasonic wave in an embodiment of theinvention.

FIG. 5 is a schematic view illustrating the outline of an example of amethod of transmitting and receiving an ultrasonic wave according to anembodiment of the invention.

FIG. 6 is a schematic view illustrating an example of an ultrasoundprobe, a puncture guideline, and a specularly reflected ultrasonic wavefrom a puncture needle displayed on a display in a method according toan embodiment of the invention.

FIG. 7A is a schematic view illustrating a method of transmitting andreceiving an ultrasonic wave of the related art in an ultrasounddiagnostic apparatus of the related art, and FIG. 7B is a schematic viewillustrating the outline of another example of a method of transmittingand receiving an ultrasonic wave in an ultrasound diagnostic apparatusaccording to an embodiment of the invention.

FIG. 8 is a schematic view illustrating the outline of another exampleof a method according to an embodiment of the invention.

FIG. 9 is a schematic view illustrating the outline of another exampleof a method according to an embodiment of the invention.

FIG. 10 is a schematic view illustrating the outline of another exampleof a method according to an embodiment of the invention.

FIG. 11 is a schematic view illustrating the outline of another exampleof a method according to an embodiment of the invention.

FIG. 12 is a flowchart showing an example of a method of transmittingand receiving an ultrasonic wave according to an embodiment of theinvention.

DETAILED DESCRIPTION OF THE INVENTION

Hereinafter, an ultrasound diagnostic apparatus, a method oftransmitting and receiving an ultrasonic wave, a program fortransmitting and receiving an ultrasonic wave, and a recording mediumaccording to the invention will be described in detail on the basis ofpreferred embodiments shown in the accompanying drawings.

Embodiment 1

FIG. 1 is a perspective view showing an example of the mainconfiguration of an ultrasound diagnostic apparatus according toEmbodiment 1 of the invention which executes a method of transmittingand receiving an ultrasonic wave according to the invention. Here, acase will be described where an ultrasound probe serving as a probe, anultrasound diagnostic apparatus body which performs control of theultrasound probe and analysis of an obtained ultrasonic echo signal, andsynthesizes an ultrasound diagnostic image, and a display which displaysa synthesized image are separately provided. A puncture adapter isattached to the ultrasound probe.

As shown in FIG. 1, an ultrasound diagnostic apparatus 10 according toEmbodiment 1 of the invention executes a method of transmitting andreceiving an ultrasonic wave according to the invention, and includes anultrasound probe (hereinafter, simply referred to as a probe) 12, anultrasound diagnostic apparatus body (hereinafter, simply referred to asan apparatus body) 14, an input unit 16, and a display 18.

The ultrasound diagnostic apparatus 10 of this embodiment also includesa puncture adapter 20 which is used in a state of being attached to theprobe 12. The ultrasound diagnostic apparatus 10 is configured so as tobe easily movable by a cart 22.

The probe 12 is a probe in which transmission and reception of anultrasonic wave are performed by a plurality of ultrasound transducers13 of a one-dimensional or two-dimensional transducer array, and is usedin a state where an array portion at the tip thereof having a pluralityof ultrasound transducers 13 arranged thereon abuts on the surface of ahuman subject. Each ultrasound transducer 13 transmits an ultrasonicwave toward the subject on the basis of an activation signal to beapplied, receives an ultrasonic echo reflected by the subject, andoutputs a reception signal.

Each ultrasound transducer 13 is constituted by a vibrator in whichelectrodes are formed at both ends of a piezoelectric material(piezoelectric body), such as piezoelectric ceramic represented by PZT(Pb (lead) zirconate titanate) or a piezoelectric polymer represented byPVDF (polyvinylidene difluoride). If a pulsed or continuous-wave voltageis applied across the electrodes of the vibrator, the piezoelectric bodyexpands and contracts. With the expansion and contraction, pulsed orcontinuous ultrasonic waves are produced from the vibrators, and theultrasonic waves are synthesized to form an ultrasonic beam. Whenreceiving the propagating ultrasonic waves, the vibrators expand andcontract to produce electric signals. The electric signals are outputsas the ultrasonic reception signals.

As the type of the ultrasound probe 12, there are various types, such asa convex type, a linear scan type, and a sector scan type.

The probe 12 is connected to the apparatus body 14 by a cable 24, andthe operation thereof is controlled by the apparatus body 14.

The detachable and replaceable puncture adapter 20 is attached to theprobe 12.

The puncture adapter 20 is attached to the probe 12, and serves as aguide which allows a puncture needle to be inserted into a target siteof the subject, such as a human subject, at a specific angle.Specifically, the puncture needle moves along a puncture provided in thepuncture adapter 20 to move in a specific insertion direction set inadvance, and the tip of the puncture needle is inserted into the targetsite of the subject. In the puncture adapter 20, the size of the usablepuncture needle, the insertion angle at which the puncture needle isinserted into the human subject, the adjustment range, the insertionposition, the insertion path, or the like differs depending on the type.The puncture adapter 20 is replaced, thereby changing the size of theusable puncture needle, the insertion angle, the range, the insertionposition, the insertion path, or the like. In the case of the punctureadapter 20 in which the size of the usable puncture needle and theinsertion angle are defined in advance, a storage unit may be providedin the puncture adapter 20, and information relating to the size of theusable puncture needle and the insertion angle may be stored in thestorage unit in advance as puncture adapter information.

The apparatus body 14 has a function of performing overall control ofthe operations of the respective units of the ultrasound diagnosticapparatus 10. In the apparatus body 14, an ultrasonic wave istransmitted and received by the probe 12, and a tomographic image isproduced from a received echo and displayed on the display 18. Theapparatus body 14 produces a B-mode image or an M-mode image as atomographic image and displays the B-mode image or the M-mode image onthe display 18 in real time. The detailed configuration of the apparatusbody 14 will be described below.

The input unit 16 includes a keyboard, a pointing device, or variousbuttons or dials for inputting various kinds of information. Anoperator, such as a physician or a technician, operates the ultrasounddiagnostic apparatus 10 using the input unit 16. For example, theoperator designates various setting values relating to the operationmode of the ultrasound diagnostic apparatus 10 according to a site underobservation using the input unit 16 or changes the depth of the focus ofthe ultrasonic beam transmitted from the probe 12. The operatordesignates a region of interest (ROI) using the input unit 16. Theoperator inputs puncture adapter information (insertion angle) of thepuncture adapter 20 using the input unit 16. When information relatingto the size of the usable puncture needle and the insertion angle isstored in the storage unit of the puncture adapter 20 in advance, it isnot necessary to input in the input unit 16.

The display 18 is, for example, a raster scan-type LCD or the like, anddisplays an ultrasound image as a moving image or a still image on thebasis of analog-converted image signals output from the apparatus body14.

In this embodiment, respective components of the ultrasound diagnosticapparatus 10 are supported by the cart 22. That is, the apparatus body14 is placed in the cart 22 and supported by the cart 22. The input unit16 and the display 18 are attached to the upper part of the cart 22. Theprobe 12 is held in a probe holder 26 which is provided on the side ofthe cart 22, to which the input unit 16 is attached. The cable 24 whichconnects the probe 12 to the apparatus body 14 is held in a hook 28which is provided on the back of the cart 22, to which the input unit 16is attached.

The cart 22 includes four casters 30 which are used to move theultrasound diagnostic apparatus 10.

Although in this embodiment, the cart 22 which supports the respectivecomponents of the ultrasound diagnostic apparatus 10 is provided so asto move the ultrasound diagnostic apparatus 10, the invention is notlimited thereto.

FIG. 2 is a block diagram showing an example of the main configurationof an ultrasound diagnostic apparatus body of the ultrasound diagnosticapparatus shown in FIG. 1 and peripheral devices. The description of theconfiguration which has already been shown in FIG. 1 and described abovewill not be provided.

The apparatus body 14 includes a system controller 32, a transmissioncircuit 34, a multiplexer 36, a reception circuit 38, a reception datastorage unit 40, a specular-reflective component calculator 42, a signalprocessor 44, an image processor 46, and a display processor 48.

The system controller 32 controls the entire ultrasound diagnosticapparatus 10 to perform an appropriate operation.

Specifically, the system controller 32 sequentially sets, through thetransmission circuit 34 and the reception circuit 38, the transmissiondirection of an ultrasonic beam and the reception direction of anultrasonic echo with straightness in the probe 12 maintained. The systemcontroller 32 has a transmission control function of selecting atransmission delay pattern in accordance with the set transmissiondirection and a reception control function of selecting a receptiondelay pattern in accordance with the set reception direction.

The transmission delay pattern is the pattern of delay time which isimposed to the activation signal of each ultrasound transducer 13 so asto form an ultrasonic beam in a desired direction by ultrasonic wavestransmitted from a plurality of ultrasound transducers 13. The receptiondelay pattern is the pattern of delay time which is imposed to thereception signal so as to extract an ultrasonic echo from a desireddirection by ultrasonic waves received by a plurality of ultrasoundtransducers 13. A storage device which is attached to the systemcontroller 32 stores a plurality of transmission delay patterns and aplurality of reception delay patterns distinguished from each other, anda plurality of transmission delay patterns and a plurality of receptiondelay patterns are selectively used depending on desired transmissiondirection and reception direction.

The system controller 32 controls the multiplexer 36 which sets transmitapertures constituted by a plurality of ultrasound transducers 13 fortransmission and receive apertures constituted by a plurality ofultrasound transducers 13 for reception. According to this embodiment,the receive apertures and transmit apertures are set so as to bedifferent such, for example, that the receive apertures are larger thanthe transmit apertures.

The system controller 32 outputs the puncture adapter information (theinsertion angle and the like) notified from the input unit 16 or thepuncture adapter 20 to the specular-reflective component calculator 42.The system controller 32 may read out the puncture adapter informationfrom the storage unit of the puncture adapter 20 in advance to store thepuncture adapter information in the storage device of the systemcontroller 32, and read out the puncture adapter information asnecessary to output to the specular-reflective component calculator 42.

The system controller 32 outputs a reception delay pattern to the signalprocessor 44 which performs a reception focus process.

The transmission circuit 34 includes a plurality of circuitscorresponding to the maximum number of transmit apertures, and producesa plurality of activation signals which are respectively applied to aplurality of ultrasound transducers 13 set as transmit apertures throughthe multiplexer 36 by the system controller 32. At this time, it ispossible to give the delay time to each of a plurality of activationsignals on the basis of a transmission delay pattern selected by thesystem controller 32. The transmission circuit 34 adjusts the delayamount of each of a plurality of activation signals such that ultrasonicwaves transmitted from a plurality of ultrasound transducers 13 set astransmit apertures form an ultrasonic beam, and supplies the activationsignals to the probe 12.

The multiplexer 36 includes a group of a number of switches, iscontrolled by the system controller 32, and switches a plurality ofultrasound transducers set as transmit apertures or receive apertures.

With the switching of the multiplexer 36, an ultrasound transducer groupto be used (for example, maximum 96, and in a normal use, 64) from amongN (for example, 192) ultrasound transducers 13 of the probe 12 isselected and set as transmit apertures or receive apertures, anddelivery of a transmission signal from the transmission circuit 34 tothe probe 12 and delivery of a reception signal from the probe 12 to thereception circuit 38 are performed. Specifically, the multiplexer 36 isconnected to N ultrasound transducers of the probe 12 through N signallines. The multiplexer 36 is used for electronic scan, and theultrasound transducers 13 are appropriately selected as transmitapertures or receive apertures to determine the position and directionwhere an ultrasonic beam is scanned.

The reception circuit 38 includes a plurality of circuits correspondingto a maximum number of receive apertures (for example, 96). Thereception circuit 38 receives and amplifies a plurality of analogreception signals output from a plurality of ultrasound transducers 13set as receive apertures through the multiplexer 36 by the systemcontroller 32, and converts the analog reception signals to digitalreception signals (reception data).

Digital-converted reception data is sequentially stored in the receptiondata storage unit 40 which has memory capacity for accumulatingreception signal data corresponding to an ultrasound image for aplurality of frames.

The reception data storage unit 40 has a function as storage means forstoring reception data (RAW data) output from the reception circuit 38,and appropriately outputs reception data to the signal processor 44 onthe basis of a read instruction from the signal processor 44.

The specular-reflective component calculator 42 calculates informationrelating to a specular-reflective component on the puncture needle in anultrasonic beam transmitted from the probe 12 described below on thebasis of the puncture adapter information provided from the systemcontroller 32, and supplies the result (the calculated informationrelating to the specular-reflective component) to the system controller32 and the signal processor 44.

The signal processor 44 performs a reception focus process in which thedelay time is given to each of a plurality of pieces of reception dataon the basis of a reception delay pattern selected by the systemcontroller 32, and these pieces of reception data are added. With thisreception focus process, the focus of an ultrasonic echo is narrowed toform reception data (sound ray data).

Next, the signal processor 44 performs a detection process, such as anenvelope detection process or a quadrature detection process, on soundray data, and then corrects attenuation depending on the distance inaccordance with the depth of the reflection position of the ultrasonicwave by STC (Sensitivity Time gain Control).

The image processor 46 produces image data representing a B-mode imageand outputs image data to the display processor 48. Specifically, theimage processor 46 subjects sound ray data read out from the signalprocessor 44 to a preprocess, such as logarithmic compression or gainadjustment, and a scan line conversion process for converting sound raydata to image data based on a normal television signal scan system toproduce a B-mode image.

The display processor 48 produces a video signal for displaying a screenon the display 18 and outputs the video signal to the display 18.

The display 18 displays a screen including an ultrasound image outputfrom the display processor 48, a measurement result, and the like toprovide various kinds of information to the operator.

Next, the outline and principle of the operation of the ultrasounddiagnostic apparatus 10 of this embodiment, and the method oftransmitting and receiving an ultrasonic wave according to the inventionwill be described.

FIG. 3 is a schematic view showing the geometric relationship between atransmitted wave and a reflected wave of an ultrasonic wave in anultrasound probe of the related art. For simplification of description,it is shown that there is no refraction in the body surface of a subjectB1 (the same applied to the subsequent drawings).

The puncture needle is formed of metal and is significantly different inacoustic impedance from surrounding subject tissues. For this reason, itis considered that an image of the puncture needle is prominentlyobtained in an ultrasound image. However, actually, if an ultrasoundimage is captured, the puncture needle does not form an image so as tobe distinguished from other tissues. To the contrary, there are manycases where the puncture needle is intermittently viewed. Accordingly,the inventors have conducted careful studies and have found thefollowings.

That is, as shown in FIG. 3, if ultrasonic waves transmitted from aplurality of ultrasound transducers 13 of the probe 12 toward thesubject B1 enter the subject B1, abut on a puncture needle N1, and arespecularly reflected by the puncture needle N1, there is a situation inwhich reflected waves are out of the reception range of the probe 12.For example, an ultrasonic wave transmitted from P1 enters the subjectB1 in an incident wave direction indicated by a reference sign “a” inFIG. 3 and is reflected by the puncture needle N1 in specular reflectionin a direction indicated by a reference sign “b” in FIG. 3, while thereflected wave having an intensity distribution indicated by a referencesign “I” in FIG. 3 is received at P1′. A normal ultrasonic echo signalreflected by a subject tissue travels in a direction indicated by areference sign “c” in FIG. 3 and is received at P1.

However, an ultrasonic wave transmitted from P2 is specularly reflectedby the puncture needle N1, reaches P2′, and is thus out of the receptionrange of the probe 12. From this, the phenomenon in which, if a part orthe whole of a reflected wave escapes and does not reach the probe 12,an image of the puncture needle N1 in an ultrasound image is difficultto view will be described.

In general, it is postulated that, in an ultrasound diagnostic techniquein which a tissue of an organism is postulated as a subject, a normalultrasonic echo signal (for example, having a point-reflectivecomponent) which is obtained when an ultrasonic wave is reflected by thetissue of the organism is received, and an image is formed from theultrasonic echo signal. However, in general, the puncture needle is ametallic body, and the surface thereof is smooth. In this case, it ispredicted that the reflection characteristic of an ultrasonic wave inthe surface of the puncture needle is significantly different from thetissue of the organism, and specular reflection is prominent. Sinceultrasonic waves emitted from a plurality of ultrasound transducers ofthe ultrasound probe are specularly reflected in the smooth surface ofthe puncture needle, in the ultrasound diagnostic apparatus of therelated art, when a signal in which a normal ultrasonic echo signal(also referred to as a point-reflective component) reflected from thetissue of the organism and a specular-reflective component specularlyreflected from the surface of the puncture needle are superimposed isreceived using the ultrasound probe arranged in the body surface of theorganism as a subject to simultaneously collect information regardingthe tissue of the organism and information regarding the tip portion ofthe puncture needle, it is difficult to constantly observe the tipportion of the puncture needle as a clear image on ultrasound imagedata.

Accordingly, with regard to the ultrasound diagnostic apparatus whichcan catch a reflected wave reaching P2′ in FIG. 3, the inventors haveobtained the following findings. First, the first finding resides inthat an ultrasound probe having a long reception range compared to therelated art, specifically, an ultrasound probe in which an array portionwith ultrasound transducers arranged therein is long compared to therelated art is manufactured. However, this is not sufficient. Forexample, although an ultrasound probe having 256 ultrasound transducershas a comparatively long array portion, in a normal method oftransmitting and receiving an ultrasonic wave, there are many caseswhere, with regard to single transmission and reception, only 64ultrasound transducers corresponding to ¼ of 256 are used to set 64channels, or a shorter number of channels may be set.

Accordingly, an intrinsic problem does not refer to the length of thearray portion but to whether or not the range in which ultrasonic wavestransmitted from transmit apertures set on a plurality of ultrasoundtransducers of the ultrasound probe and specularly reflected on thesurface of the puncture needle are predicted to reach is covered byreceive apertures set on a plurality of ultrasound transducers of theultrasound probe. Accordingly, the second finding of the inventorsresides in that the range in which a specularly reflected wave reachesis predicted, and the receive apertures of the ultrasound probe are setso as to be different from the transmit apertures, e.g., larger than thetransmit apertures, on the basis of the prediction result, so that theultrasound probe can cover (receive) a specularly reflected wave. Thetransmit apertures and the receive apertures are set on a plurality ofultrasound transducers, and mean the positions of the ultrasoundtransducer and the number of ultrasound transducers (the number ofchannels) for reception.

The specularly reflected wave (also referred to as a specular-reflectivecomponent) from the puncture needle is to be only taken into account inorder to only obtain the image of the puncture needle. To begin with,since paracentesis is an action where there is an object (subjecttissue) of paracentesis, and the puncture needle is inserted toward theobject, it is important to obtain images of the object of paracentesisand surrounding tissues. In this case, it is necessary for an ultrasounddiagnostic apparatus not only to cover the specular-reflective componentof the puncture needle but also to sufficiently receive the normalultrasonic echo signal reflected from the normal subject tissue.

FIG. 4 is a schematic view illustrating the basic concept of a method oftransmitting and receiving an ultrasonic wave according to an embodimentof the invention which is executed by the ultrasound diagnosticapparatus of this embodiment.

FIG. 4 shows a transmit aperture T1 and a receive aperture R1 of theprobe 12, and similarly to an ultrasound diagnostic apparatus of therelated art, a receive aperture R2 for receiving the normal ultrasonicecho signal (point-reflective component) reflected from a subject tissueor the like coincides with the transmit aperture T1. Meanwhile, areceive aperture R3 for receiving the specular-reflective component fromthe puncture needle N1 does not coincide with the transmit aperture T1and is expanded rightward in FIG. 4. More specifically, the receiveaperture R3 is set so as to include those of the ultrasound transducers13 located on the opposite side with respect to the transmit aperture T1from the insertion position at which the puncture needle N1 is insertedinto the subject B1, so that the receive aperture R3 is set on two ormore of the ultrasound transducers 13 located in positions to receivethe specular-reflective component of the ultrasonic beam reflected bythe puncture needle N.

In the method of transmitting and receiving an ultrasonic wave of thisembodiment, a synthetic aperture in which both the receive aperture R2for the normal ultrasonic echo signal and the receive aperture R3 forthe specular-reflective component are combined is the receive apertureR1. Thus, the receive aperture R1 extends more toward the opposite sidewith respect to the transmit aperture T1 from the insertion position ofthe puncture needle N1 into the subject B1 as compared with the typeknown in the art. In this way, the apparatus body 14 uses a mode inwhich the position and width (the number of channels) of the receiveaperture R1 of the probe 12 are changed in accordance with thespecular-reflective component of the puncture needle.

Although only the normal ultrasonic echo signal substantially reachesthe receive aperture R2 for the normal ultrasonic echo signal, it willbe obvious that the specular-reflective component and the normalultrasonic echo signal reach the receive aperture R3 for thespecular-reflective component.

FIG. 5 is a schematic view showing an example of a method of predictinga range where an ultrasonic wave specularly reflected on the punctureneedle reaches in this embodiment.

If the insertion angle of the puncture needle N1 into the subject B1 isθ₁, the center position of an ultrasound transmission beam is P11, thedepth from the surface of the subject B1 to the puncture needle N1 atthe center position P11 is D₁, a point at which a reflected wave isreceived by the ultrasound transducer after specular reflection occurson the puncture needle N1 at the depth D₁ from the center position P11of the ultrasound transmission beam is P11′, and the distance from thecenter position P11 of the ultrasound transmission beam to the insertionposition of the puncture needle is W₁, the distance L₁ between the pointP11′ to which a reflected wave returns and the center position P11 ofthe transmission beam is calculated by Expression (1).

$\begin{matrix}\begin{matrix}{L_{1} = {D_{1}\tan\; 2\;\theta_{1}}} \\{= {W_{1}\tan\;\theta_{1}\tan\; 2\theta_{1}}}\end{matrix} & (1)\end{matrix}$

Accordingly, it is preferable to determine the width of the receiveaperture taking into consideration the point P11′ to which a reflectedwave returns. For example; in the normal transmission and receptionwithout taking into consideration the puncture needle N1, the transmitaperture T1 and the receive aperture R2 (see FIG. 4) are set in 64elements, and when receiving an echo signal based on a reflected wave ofthe puncture needle N1, the receive aperture R1 (see FIG. 4) is extendedtoward the reaching point P11′ of the reflected wave to set the numberof receive apertures to, for example, the maximum number, say 96elements. In particular, when an ultrasound transmission beam is formedon the rightmost end of the transmit aperture, a point at the rightmostend to which a reflected ultrasonic wave of the ultrasound transmissionbeam returns is a critical point, and in a best state, the receiveaperture covers this point.

When it is also necessary to take into consideration the influence ofrefraction in the body surface of the subject B1 or inside the subjectB1, it is preferable to perform calculation in accordance with theSnell's law.

Information necessary for determining the width of the receive aperture,for example, in the above-described example, positional information ofthe point P11′ to which a reflected wave returns is produced asspecular-reflective component information in the specular-reflectivecomponent calculator 42. The signal processor 44 determines a method ofprocessing reception data from the reception data storage unit 40 on thebasis of this information, and the system controller 32 controls aswitching method in the multiplexer 36.

The insertion angle θ₁ of the puncture needle N1 into the ultrasoundtransducer array is supplied from the system controller 32 to thespecular-reflective component calculator 42 as puncture adapterinformation. When the puncture adapter 20 is attached to the probe 12,as shown in FIG. 6, a puncture guideline G which is used to guide thepuncture needle N1 may be displayed on the display 18, and the insertionangle θ₁ of the puncture needle N1 may be known to the technician as anangle between the puncture guideline G and the surface of the subjectB1.

Though not shown, the apparatus body 14 may be separately provided witha puncture needle detector so that the insertion angle is determined onthe basis of positional information of the puncture needle which isautomatically recognized by the puncture needle detector on the basis ofthe ultrasound image and is output from the puncture needle detector.

As described above, in the ultrasound diagnostic apparatus and themethod of transmitting and receiving an ultrasonic wave according toEmbodiment 1 of the invention, the width of the receive aperture (thenumber of channels) is determined on the basis of the positionalrelationship between the puncture needle and the ultrasound probe, andbeam forming is performed for a reception signal obtained in thecorresponding receive aperture. Accordingly, since it is possible toimprove display resolution of an ultrasound image including the insertedpuncture needle, visibility of the puncture needle is improved. The mostimportant parameter of information representing the positionalrelationship between the puncture needle and the ultrasound probe is theangle between the traveling direction of a transmitted ultrasonic waveand the puncture-needle, that is, the insertion angle of the punctureneedle.

In this embodiment, a mode has been described where the receive apertureis expanded compared to that in the related art in order to receive thespecular-reflective component and the normal ultrasonic echo signal(point-reflective component). However, for example, when weight is notgiven to the normal ultrasonic echo signal, a mode may be used in whichthe position of the receive aperture is changed on the basis ofspecular-reflective component information.

Although in this embodiment, a case has been described where the widthof the receive aperture is changed (for example, a change from 64elements to 96 elements), the position of the receive aperture may bechanged such that the center position in the transmission beam directionand the reaching position of the specular-reflective component from thepuncture needle are contained in the receive aperture. The receiveaperture for receiving an ultrasonic echo from the transmission beamdirection and the receive aperture for the reaching position of thespecular-reflective component from the puncture needle may be separatelyset.

Embodiment 2

An ultrasound diagnostic apparatus according to Embodiment 2 of theinvention has a reception apodization function added to the signalprocessor 44 of the apparatus body 14 of the ultrasound diagnosticapparatus 10 in Embodiment 1. The configuration of the ultrasounddiagnostic apparatus of this embodiment is substantially the same as theultrasound diagnostic apparatus 10 shown in FIGS. 1 and 2, except thereception apodization function, and thus description in connection withthe drawings will not be provided. Hereinafter, in the detaileddescription of the ultrasound diagnostic apparatus of this embodiment,the same components as those of the ultrasound diagnostic apparatus 10shown in FIG. 2 are denoted by the same reference numerals.

Reception apodization is a technique which gives weighting factors to aplurality of pieces of reception data before an addition process isperformed. Specifically, the largest weight is set for a receptionsignal from an ultrasound transducer at the center of an ultrasonicbeam, and a smaller weight is set for a reception signal with anincreasing distance from the center. Thus, it is possible to perform areception process while a reception signal directly reaching from atarget under observation which will be at the center of the ultrasonicbeam is most highlighted, such that a received ultrasonic beam can havehigh precision.

FIG. 7A is a schematic view showing a method of transmitting andreceiving an ultrasonic wave of the related art which is executed by anultrasound diagnostic apparatus of the related art. FIG. 7B is aschematic view showing the outline of an example of a method oftransmitting and receiving an ultrasonic wave of this embodiment whichis executed by the ultrasound diagnostic apparatus of this embodiment.FIG. 7A shows the outline of reception apodization of the related art.Usually, the peak of a weighting curve W21 of reception apodization andthe center position C21 of a transmission beam are set to coincide witheach other.

FIG. 7B shows the outline of reception apodization of this embodiment.As will be understood from FIG. 7B, in this embodiment, a weighing curveW22 of reception apodization has two peaks. One peak is set to coincidewith the center position C22 of the transmission beam, and another peakis set at the center position C23 of the specular-reflective componentfrom the puncture needle. The center position C23 of thespecular-reflective component is set at a position distant from thecenter position C22 of the transmission beam by D₁ tan 2θ₁ by Expression(1). The reception apodization process is performed before the additionprocess in the reception focus process by the signal processor 44 of theapparatus body 14 shown in FIG. 2.

In this way, with regard to the weight setting by reception apodization,two peaks, that is, two sites where a reception signal is to behighlighted are set, thereby obtaining an image of a subject tissue withhigh precision and also obtaining an image of a puncture needle withhigh precision.

As described above, according to the ultrasound diagnostic apparatus ofthis embodiment, reception apodization is performed on both thetransmission beam center position and the reaching position of thespecular-reflective component on the puncture needle. Therefore, it ispossible to perform a highlight process on reception signals of bothtargets under observation and to further improve display resolution ofan ultrasound image including the inserted puncture needle.

Although in this embodiment, a mode has been described in which twopeaks are set by the weight setting through reception apodization, forexample, when weight is not given to the normal ultrasonic echo signal(point-reflective component) from the subject tissue, a mode in which apeak is set for only the specular-reflective component may be used.

In FIG. 7B, a mode has been described in which two peaks draw the samenormal curve in the weighting curve W22 of reception apodization.However, a case where a weighting curve is different between the subjecttissue and the puncture needle is also considered and therefore aweighting curve appropriate for the needle may be applied to thespecular-reflective component.

Although the weighting curve W22 having two peaks is used in theembodiment shown in FIG. 7B to effect reception apodization for both thetransmission beam center position and the position at which thespecular-reflective component arrives from the puncture needle, theinvention is not limited thereto; to effect reception apodization forthe individual positions, a weighting curve having a single peak may beused for each of these positions.

An embodiment shown in FIG. 8, for example, uses a weighting curve W23having a single peak so set as to coincide with the transmission beamcenter position C22 to effect reception apodization for the transmissionbeam center position and a weighting curve W24 having a single peak soset as to coincide with the center position C23 of thespecular-reflective component reflected by the puncture needle to effectreception apodization for the position at which the specular-reflectivecomponent reflected by the puncture needle arrives.

Accordingly, since the reception data containing the normal ultrasonicecho signal from the subject tissue (hereinafter referred to also assubject tissue component) and the specular-reflective component from thepuncture needle are stored in the reception data storage unit 40 in thisembodiment, the signal processor 44 effects reception apodization forenhancing the subject tissue component using the weighting curve W23(subject tissue enhancement processing) and reception apodization forenhancing the specular-reflective component from the puncture needleusing the weighting curve W24 (specular-reflective component enhancementprocessing) for the same reception data stored, and the image processor46 synthesizes the individually enhanced reception data. Enhancementprocessing such as filtering processing may be performed before thesynthesis. Thus, optimal image processing for the subject tissuecomponent and the specular-reflective component from the puncture needleis made possible as the same reception data stored in the reception datastorage unit 40 is used repeatedly.

The weighting curves W23 and W24 used for reception apodization areexamples each having a peak exhibiting a normal curve similar to eachother but the invention is not limited thereto; the peaks may differ,provided that the weighting curves used are appropriate for the subjecttissue component and the specular-reflective component from the punctureneedle.

Embodiment 3

An ultrasound diagnostic apparatus according to Embodiment 3 of theinvention has an aperture synthesis function different from that ofEmbodiment 1 added to the apparatus body 14 of the ultrasound diagnosticapparatus 10 in Embodiment 1. The configuration of the ultrasounddiagnostic apparatus of this embodiment is substantially the same asthat of the ultrasound diagnostic apparatus 10 shown in FIGS. 1 and 2,except that the aperture synthesis function is different, and thusdescription in connection with the drawings will not be provided.Hereinafter, in the detailed description of the ultrasound diagnosticapparatus of this embodiment, the same components as those of theultrasound diagnostic apparatus 10 shown in FIG. 2 are denoted by thesame reference numerals.

The aperture synthesis technique for use in this embodiment is thetechnique which is described in commonly assigned JP 2010-29374 A.Specifically, according to this technique, an ultrasonic beam istransmitted multiple times, ultrasonic echo signals generated arereceived by a plurality of ultrasound transducers in a plurality ofdifferent receive apertures, reception signals are temporarily stored ina memory, reception signals obtained in different receive aperture aresynthesized, and a reception focus process is performed on a resultantreception signal.

FIG. 9 is a schematic view illustrating the outline of an example of amethod of transmitting and receiving an ultrasonic wave of thisembodiment which is executed by the ultrasound diagnostic apparatus ofthis embodiment. In this embodiment, a transmit aperture and a receiveaperture 1 coincide with each other, and an ultrasonic beam transmittedfrom the transmit aperture is specularly reflected by the punctureneedle N1. In the case of FIG. 9, the ultrasonic beam returns to areceive aperture 2, not the receive aperture 1. For this reason, when itis determined that an aperture synthesis process should be performed inthe ultrasound diagnostic apparatus of this embodiment, an ultrasonicbeam is transmitted using the same transmit aperture twice. In the firstreception, a reception process is performed in the receive aperture 1 totemporarily store reception data in the reception data storage unit 40,and in the second reception, the ultrasound transducers 13 are switchedby the multiplexer 36, and a signal is received in the receive aperture2. Thereafter, the signals obtained in the two receptions in total aresynthesized.

In the ultrasound diagnostic apparatus of this embodiment, thedetermination of whether or not the aperture synthesis process should beperformed is made by the system controller 32 on the basis ofspecular-reflective component information provided from thespecular-reflective component calculator 42. Specifically, the systemcontroller 32 determines that the aperture synthesis of the receiveaperture 1 and the receive aperture 2 will be performed when Expression(2) is satisfied such that the normal ultrasonic echo signal(point-reflective component) from the transmission beam direction andthe specular-reflective component from the puncture needle N1 arereceived with a sufficient receive aperture width.D ₁ tan 2θ₁≧(receive aperture width)/2  (2)

In the aperture synthesis process, the transmission process of anultrasonic beam multiple times is realized when the system controller 32controls the multiplexer 36 and the transmission circuit 34. In theaperture synthesis process, the reception process by a plurality ofdifferent apertures is realized when the system controller 32 controlsthe multiplexer 36, the reception circuit 38, the reception data storageunit 40, and the signal processor 44. The signal processor 44 performs acorresponding reception focus process on reception data sent from areception system, such as the reception circuit 38, to obtainaperture-synthesized reception data.

As described above, according to the ultrasound diagnostic apparatus ofthis embodiment, element data of the receive aperture 1 where the normalultrasonic echo signal (point-reflective component) from the subjecttissue B1 is prominent and element data of the receive aperture 2 wherethe specular-reflective component from the puncture needle N1 isprominent are subjected to aperture synthesis, thereby obtainingreception signals of both targets under observation and also furtherimproving display resolution of an ultrasound image including theinserted puncture needle.

Embodiment 4

The ultrasound diagnostic apparatus according to Embodiment 4 of theinvention has an aperture synthesis function different from that ofEmbodiment 3 added to the apparatus body 14 of the ultrasound diagnosticapparatus 10 described in Embodiment 1. As described above, differentfrom above Embodiment 3, the receive apertures according to thisembodiment correspond to those of the above Embodiment 1 as divided intoreceive apertures for receiving an ultrasonic echo signal from thetransmission beam direction (point-reflective component) and receiveapertures for the position at which the specular-reflective componentreflected by the puncture needle arrives for one transmission. Similardescriptions therefore will be omitted and differences will mostly bedescribed.

FIG. 10 is a schematic view illustrating the outline of an example ofthe method of transmitting and receiving an ultrasonic wave according tothis embodiment implemented by the ultrasound diagnostic apparatus ofthis embodiment.

The receive apertures set in this embodiment are a receive aperture Acentered on the transmission direction and a receive aperture B centeredon the ultrasound transducers for the specular-reflective component, thereceive apertures A and B being divided from each other by at least oneultrasound transducer 13 not used as receive aperture, each of thesereceive apertures A and B including a plurality of ultrasoundtransducers 13.

According to this embodiment, the transmit apertures and the receiveaperture A coincide, and the ultrasonic beam transmitted from thetransmit apertures is reflected by a normal subject tissue and returnedto the receive aperture A as normal ultrasonic echo signal(point-reflective component), while the specularly reflected wave(specular-reflective component) reflected by the puncture needle N1 inspecular reflection (mirror reflection) is returned not to the receiveaperture A but to the receive aperture B. Thus, in the ultrasounddiagnostic apparatus according to this embodiment, a normal ultrasonicecho signal can be received by the receive aperture A, and thespecular-reflective component from the puncture needle N1 can bereceived by the receive aperture B. According to this embodiment, thetransmit apertures and the receive aperture A need not necessarilycoincide.

Thus, according to this embodiment, ultrasonic echo signals received bythe two receive apertures A and B are synthesized, that is, aperturesynthesis processing by the receive aperture A and the receive apertureB is performed, to synthesize the images of the subject tissue B1 andthe puncture needle N1.

The reason for locating at least one element of the ultrasoundtransducers 13 not used as receive aperture between the receive apertureA and the receive aperture B is to ensure that a signal immediatelybeneath a transmit aperture where a normal image signal is strong and asignal where the specular-reflective component from the puncture needleis strong are received, one distinctly separate from the other even witha portable low-cost type having only a small number of elements in areception circuit.

According to this invention, since a normal ultrasonic echo signal andthe specular-reflective component from the puncture needle N1 in onetransmission of the ultrasonic beam can be received by the two dividedreceive apertures A and B, an apparatus having only a small number ofchannels can receive the specular-reflective component. Settings of thetwo divided receive apertures A and B on a number ofultrasound-transducers 13 can be readily made by the multiplexer 36.

According to this embodiment, an image with an enhanced puncture needlevisibility can be provided without lowering the frame rate, which isimportant when the puncture needle is inserted, by temporarily storingthe reception echo signal as reception data (reception data received bythe individual ultrasound transducers 13, which may also be referred tosimply as element data below) in the reception data storage unit 40,performing reception beam forming in two or more directions includingthe transmission beam direction and the puncture needlespecular-reflection direction from the element data in one transmission,and synthesizing and displaying data of these, ultrasonic echo signaldata.

Thus, according to the above Embodiment 3, a plurality of ultrasonicbeam transmission processings are performed and, for every transmittedultrasonic beam, aperture synthesis processing is performed whereby anormal ultrasonic echo signal (point-reflective component) and aspecular-reflective component from the puncture needle N1 are receivedby a plurality of different apertures and synthesized. According to thisembodiment, on the other hand, the echo signals in the transmission beamdirection and the puncture needle specular reflection direction can bereceived by the receive aperture A and the receive aperture B in onetransmission, so that the frame rate is not lowered as compared with theabove Embodiment 3 wherein the echo signals in the transmission beamdirection and the puncture needle specular reflection direction arereceived by the receive aperture 1 and the receive aperture 2respectively in a plurality of transmissions, and, moreover, there is noneed to switch between the transmit apertures and the receive aperture1, and the transmit apertures and the receive aperture 2 through themultiplexer 36 as required in the above Embodiment 3, thereby enablingeasy and quick switching of the two receive apertures A and B by themultiplexer 36 from the transmit apertures. Thus, such problems as delayin switching timing that may possibly occur in the above Embodiment 3can be eliminated.

Further, according to this embodiment, since the element data of thereceive aperture A where the normal ultrasonic echo signal from thesubject tissue B1 (point-reflective component) is a major component andthe element data of the receive aperture B where the specular-reflectivecomponent from the puncture needle N1 is a major component are combinedin the aperture synthesis processing, the reception signals of bothsubjects of observation can be obtained, thereby increasing the displayresolution of an ultrasound image with an inserted puncture needle.

Embodiment 5

An ultrasound diagnostic apparatus according to Embodiment 4 of theinvention is different from the ultrasound diagnostic apparatus 10 ofEmbodiment 1 in that the probe 12 has a function of transmitting anultrasonic beam with a deflection angle (see FIG. 11), not in adirection perpendicular to the array direction of the ultrasoundtransducers 13. Except for this point, the ultrasound diagnosticapparatus of this embodiment is Substantially the same as the ultrasounddiagnostic apparatus 10 shown in FIGS. 1 and 2, and thus description inconnection with the drawings will not be provided. An apparatus body ofthe ultrasound diagnostic apparatus of this embodiment has aconfiguration corresponding to the novel function. Hereinafter, in thedetailed description of the ultrasound diagnostic apparatus of thisembodiment, the same components as those of the ultrasound diagnosticapparatus 10 shown in FIG. 2 are denoted by the same reference numerals.

FIG. 11 is a schematic view illustrating an example of a method ofpredicting a range in which, in an ultrasonic beam transmitted with adeflection angle, a specularly reflected wave (specular-reflectivecomponent) of an ultrasonic wave from a puncture needle reaches.

If the insertion angle of the puncture needle N1 into the subject B1 isθ₂, a point at which a reflected wave is emitted from the subject B1after an ultrasonic wave having entered at an inclination angle φ₂ froman entrance position P41 of the ultrasonic wave caused specularreflection on the puncture needle N1 at a depth D₂ is P41′, and thedistance from the entrance position P41 of an ultrasonic wave to theinsertion position of the puncture needle N1 is W₂, the distance L₂between the point P41′ to which the reflected wave returns and theentrance point P41 is calculated by Expression (3).

Accordingly, in the ultrasound diagnostic apparatus of this embodiment,it is preferable to determine the width of the receive aperture takinginto consideration of the point P41′ to which the reflected wavereturns.

$\begin{matrix}{\begin{matrix}{L_{2} = {{D_{2} \cdot \cos}\;\phi_{2}\left\{ {{\tan\left( {{2\theta_{2}} - \phi_{2}} \right)} - {\tan\;\phi_{2}}} \right\}}} \\{= {W_{2} \cdot \frac{\tan\;\theta_{2}\left\{ {{\tan\left( {{2\theta_{2}} - \phi_{2}} \right)} - {\tan\;\phi_{2}}} \right\}}{{\tan\;{\theta_{2} \cdot \tan}\;\phi_{2}} + 1}}}\end{matrix}\left( {W_{2} = {D_{2} \cdot \frac{\cos\;\phi_{2}\left\{ {{\tan\;{\theta_{2} \cdot \tan}\;\phi_{2}} + 1} \right\}}{\tan\;\theta_{2}}}} \right)} & (3)\end{matrix}$

As described above, according to the ultrasound diagnostic apparatus andthe apparatus body of this embodiment, even when an ultrasonic beam istransmitted from the ultrasound probe with an inclination angle, it ispossible to determine the position and width (the number of channels) ofthe receive aperture on the basis of the positional relationship betweenthe puncture needle and the ultrasound probe. Therefore, it is possibleto improve display resolution of an ultrasound image including theinserted puncture needle, thereby improving visibility of the punctureneedle.

Next, a method of transmitting and receiving an ultrasonic wave of theinvention which is executed by the ultrasound diagnostic apparatus ofthe invention will be described.

FIG. 12 is a flowchart showing an example of a method of transmittingand receiving an ultrasonic wave according to the invention.

The method of transmitting and receiving an ultrasonic wave shown inFIG. 12 is executed in the ultrasound diagnostic apparatus 10 accordingto Embodiment 1 of the invention shown in FIGS. 1 and 2. As shown inFIGS. 4 to 6, a plurality of ultrasound transducers 13 of the probe 12are used to perform transmission and reception of ultrasonic wavestoward a target site of the subject B1 containing the puncture needleN1.

It is assumed that the operator powers on the apparatus body 14 of theultrasound diagnostic apparatus 10, and abuts the probe 12 on the skinof the subject B1, such as a human subject.

First, in the method of transmitting and receiving an ultrasonic wave ofthe invention, in Step S10, an ultrasonic beam which is transmitted froma transmit aperture set on a plurality of ultrasound transducers 13 ofthe probe 12 is formed.

Next, in Step S12, the formed ultrasonic beam for transmission istransmitted toward the target site of the subject B1.

In Step S14, information relating to the specular-reflective componentof the ultrasonic beam in the puncture needle N1 is acquired.

In Step S16, a receive aperture different from the transmit aperture isset on a plurality of ultrasound transducers 13 on the basis of theinformation relating to the specular-reflective component of theultrasonic beam.

In Step S18, an ultrasonic echo signal of the ultrasonic beam isreceived by a plurality of ultrasound transducers 13 using the setreceive aperture.

Subsequently, in Step S20, the ultrasonic echo signal received by aplurality of ultrasound transducers 13 using the receive aperture isprocessed to produce an ultrasound image.

In this way, in the method of transmitting and receiving an ultrasonicwave of the invention, it is possible to reliably and thoroughlyreceive, from the receive aperture, the component of the ultrasonic beamtransmitted from the transmit aperture and specularly reflected on thepuncture needle. For this reason, in the method of the invention, it ispossible to increase the intensity of an echo signal from the punctureneedle and to improve visibility of the puncture needle.

The above-described embodiments of the invention are merely illustrativeof the invention, and are not intended to limit the configuration of theinvention. The ultrasound diagnostic apparatus and the method oftransmitting and receiving an ultrasonic wave according to the inventionare not limited to the above-described embodiments, and various changesmay be made without departing from the object of the invention.

For example, although in the embodiments, a case has been describedwhere the ultrasound diagnostic apparatus, the display, and the inputunit are separately provided, the ultrasound diagnostic apparatus, thedisplay, and the input unit may be provided as a single device.

Although the foregoing embodiment is configured by a central processingunit (CPU) and software which causes the CPU to perform variousprocesses, these may be configured by hardware, such as digital circuitsor analog circuits. Software is stored in an internal memory (notshown).

The algorithm of the method of transmitting and receiving an ultrasonicwave according to the invention is described in a programming language,and compiled as necessary. The program for transmitting and receiving anultrasonic wave is stored in a memory (storage medium) and executed byinformation processing means of another ultrasound diagnostic apparatus.Therefore, it is possible to realize the same functions as those of theultrasound diagnostic apparatus according to the invention.

That is, the program for transmitting and receiving an ultrasonic waveaccording to the invention causes a computer to execute a plurality ofsteps for transmitting and receiving an ultrasonic wave toward a site ofa subject containing a puncture needle using a plurality of ultrasoundtransducers. The steps includes the steps of forming an ultrasonic beamto be transmitted from a transmit aperture set on a plurality ofultrasound transducers, transmitting the formed ultrasonic beam towardthe target site of the subject, acquiring information relating to aspecular-reflective component of the ultrasonic beam in a punctureneedle, setting a first receive aperture different from the transmitaperture on a plurality of ultrasound transducers on the basis of theinformation relating to the specular-reflective component of theultrasonic beam, receiving an ultrasonic echo signal of the ultrasonicbeam by a plurality of ultrasound transducers using the set firstreceive aperture, and processing the ultrasonic echo signal received bya plurality of ultrasound transducers using the first receive aperture.

It will be obvious that the invention may be implemented as a computerreadable recording medium having the program for transmitting andreceiving an ultrasonic wave recorded thereon.

The ultrasound diagnostic apparatus, the method of transmitting andreceiving an ultrasonic wave, and the program for transmitting andreceiving an ultrasonic wave according to the embodiments of theinvention can be used for the purpose of, for example, paracentesis inwhich the puncture needle is inserted into the subject while viewing theultrasound image.

What is claimed is:
 1. An ultrasound diagnostic apparatus comprising: aplurality of ultrasound transducers which performs transmission andreception of ultrasonic waves toward a target site of a subject thatcontains a puncture needle; a transmission computing unit configured toform an ultrasonic beam to be transmitted from a transmit aperture seton the plurality of ultrasound transducers; an acquisition unitconfigured to acquire information that relates to a specular-reflectivecomponent of the ultrasonic beam in the puncture needle; a receptioncomputing unit configured to set a receive aperture different from thetransmit aperture set on the plurality of ultrasound transducers on thebasis of the information that relates to the specular-reflectivecomponent of the ultrasonic beam; and a reception signal processorconfigured to process an ultrasonic echo signal received by theplurality of ultrasound transducers set as the receive aperture, whereinthe reception computing unit sets as the receive aperture a firstreceive aperture that receives the specular-reflective component of theultrasonic beam from the puncture needle and a second receive aperturethat receives a point-reflective component of the ultrasonic beam from asubject tissue, the first receive aperture being different from thesecond receive aperture, and wherein the reception signal processorsynthesizes a first ultrasonic echo signal of the specular-reflectivecomponent receiving through the first receive aperture and a secondultrasonic echo signal of the point-reflective component receivingthrough the second receive aperture in accordance with one transmissionby the transmit aperture.
 2. The ultrasound diagnostic apparatusaccording to claim 1, wherein the acquisition unit is configured toacquire the information that relates to the specular-reflectivecomponent from a positional relationship between the plurality ofultrasound transducers and the puncture needle.
 3. The ultrasounddiagnostic apparatus according to claim 2, wherein the acquisition unitis configured to acquire the information that relates to thespecular-reflective component from an insertion angle of the punctureneedle inserted into the subject with respect to the plurality ofultrasound transducers.
 4. The ultrasound diagnostic apparatus accordingto claim 3, wherein the transmission computing unit forms the ultrasonicbeam to be deflected, and the acquisition unit is configured to acquirethe information that relates to the specular-reflective component fromthe insertion angle of the puncture needle and a deflection angle of theultrasonic beam.
 5. The ultrasound diagnostic apparatus according toclaim 1, wherein the reception signal processor performs a weightingprocess to enhance the first ultrasonic echo signal of thespecular-reflective component.
 6. The ultrasound diagnostic apparatusaccording to claim 5, wherein the reception signal processor further hasa storage unit which temporarily stores the first ultrasonic echo signaland the second ultrasonic echo signal, performs the weighting process toenhance the second ultrasonic echo signal of the point-reflectivecomponent, and synthesizes the second ultrasonic echo signal on whichthe weighting process has thus been performed and the first ultrasonicecho signal of the specular-reflective component on which the weightingprocess has been performed.
 7. The ultrasound diagnostic apparatusaccording to claim 1, wherein the reception signal processor further hasa storage unit which temporarily stores the first ultrasonic echo signaland the second ultrasonic echo signal.
 8. The ultrasound diagnosticapparatus according to claim 1, wherein the reception computing unitsets the first receive aperture to contain ultrasound transducerslocated on a side opposite with respect to the transmit apertures froman insertion position at which the puncture needle is introduced into asubject.
 9. The ultrasound diagnostic apparatus according to claim 1,wherein the reception computing unit sets the first receive aperture andthe second receive aperture discontinuously divided on the plurality ofultrasound transducers, and wherein there is at least one ultrasoundtransducer not used as the receive aperture between the first and secondreceive apertures.
 10. An ultrasound diagnostic apparatus comprising: aplurality of ultrasound transducers which performs transmission andreception of ultrasonic waves toward a target site of a subject thatcontains a puncture needle; a transmission computing unit configured toform an ultrasonic beam to be transmitted from a transmit aperture seton the plurality of ultrasound transducers; an acquisition unitconfigured to acquire information that relates to a specular-reflectivecomponent of the ultrasonic beam in the puncture needle; a receptioncomputing unit configured to set a receive aperture different from thetransmit aperture set on the plurality of ultrasound transducers on thebasis of the information that relates to the specular-reflectivecomponent of the ultrasonic beam; and a reception signal processorconfigured to process an ultrasonic echo signal received by theplurality of ultrasound transducers set as the receive aperture, whereinthe reception computing unit sets as the receive aperture a firstreceive aperture that receives the specular-reflective component of theultrasonic beam from the puncture needle and a second receive aperturethat receives a point-reflective component of the ultrasonic beam from asubject tissue, the first receive aperture being different from thesecond receive aperture, and wherein the reception signal processorsynthesizes a first ultrasonic echo signal of the specular-reflectivecomponent receiving through the first receive aperture and a secondultrasonic echo signal of the point-reflective component receivingthrough the second receive aperture in accordance with multiple times oftransmission by the transmit aperture.